This type of actuating device is useful in numerous applications, and in some applications may even be associated with an energy recovery system or an electromagnetic braking system, for example.
For example, document FR 2 678 597 describes an actuator used in the field of robotics, and in particular an electric actuator which is advantageously substituted for a hydraulic cylinder.
This electric actuator comprises at least one electric motor and a system for recovering the kinetic energy from the device maneuvered by said actuator. The recovery system comprises electronic components and a switch for controlling and operating these recovery means.
The association of an electric motor and an electromagnetic brake, as described in another document EP 1 070 827, is commonly used for actuating shutters or blinds for example.
As described in this document, the electromagnetic brake is a hysteresis brake installed directly onto the motor shaft, between the motor and the torque converter. This brake is utilized, meaning it is made active or inactive, by a control which causes current to flow through a coil that activates or deactivates the braking function.
The above energy recovery and/or braking operations are accompanied by a supplemental effect: a damping of the movements of the device which is normally maneuvered by the electric motor. However, this form of damping requires active control, meaning there must be a positive action by the operator or some other party in order to bring it into play electrically.
For hydraulic cylinders, this damping effect is inherent in the equipment; it results both from the compressibility of the hydraulic fluid and from the general design of the cylinder. This damping does not require active control, as it is always intrinsically present.